Agent for ameliorating brain hypofunction

ABSTRACT

Provided are effective and highly safe agents, medicaments and the like for ameliorating various disorders caused by brain hypofunction. Also provided is a preventing or ameliorating agent for brain hypofunction containing N-acetyl-D-mannosamine, a pharmaceutical composition for preventing, ameliorating or treating disorders due to brain hypofunction, containing an effective amount of N-acetyl-D-mannosamine and a pharmaceutically acceptable carrier, and a food comprising N-acetyl-D-mannosamine added thereto.

This application is a continuation-in-part application based onPCT/JP2009/065438, all teachings disclosed wherein are incorporatedherein by reference.

This application claims priority to a patent application No. 2010-043308filed in Japan on Feb. 26, 2010.

TECHNICAL FIELD

The present invention relates to an agent for ameliorating brainhypofunction, more specifically to pharmaceutical use applications ofN-acetyl-D-mannosamine.

BACKGROUND ART

A large number of drugs are inducers of sleep. There are also many drugsexhibiting awakening action. However, these drugs pose problems of drugresistance and drug dependence in prolonged use. Additionally, thesedrugs do not improve “the quality of sleep” for the purpose of treatingaging-related sleep disorders. Furthermore, no drugs are available thatameliorate learning and memory disorders that develop with aging. Withthe aging of the general population, the ratio of people suffering aquantitative or qualitative reduction in their sleep is increasing.Various cerebral disorders that develop due to aging-related brainhypofunction have major difficulties not only on patients, but also onsociety as a whole.

To date, central nervous stimulants and sleep-inducing drugs have beenused for sleep disorders. Most of them target the neurotransmitterpathways, and many are short-time acting, though the persistency ofaction varies among different agents. Both central nervous stimulantsand sleep-inducing drugs have a risk to cause adverse reactions such asdependence, habituation, and transient amnesia, many of which aredesignated narcotics by law.

Sleep, one of the most fundamental physiological functions of organisms,is essential for their survival. Although its physiological significanceis still disputable, sleep is thought to be involved in higher brainfunctions such to as recovery from psychosomatic fatigue and memoryfixation and reconsolidation.

Based on electromyographic and electroencephalographic analyses, sleepcan be divided into two stages: non-REM sleep, characterized bydecreased brain function, and REM sleep, where brain function is activebut skeletal muscles are relaxed. What is called deep sleep, slow wavesleep, belongs to non-REM sleep. Although the ratio of REM and non-REMsleep stages and the length of sleep differ among different biologicalspecies, REM sleep and slow wave sleep are also observed in mice andother non-human animals.

The REM sleep stage is thought to be particularly important to ensurethat higher brain functions such as memory fixation and reconsolidationoccur normally.

Sleep disorders are roughly divided into two categories: hypersomnia andasomnia. Typical conditions are narcolepsy in the former and insomnia inthe latter. Caused by a broad range of factors, sleep disorders areinduced in case of forced time shifts such as jet lags and shift work,or with stress due to overwork and the like. Meanwhile, many cases ofsleep disorders accompany some other diseases; cardiac functionabnormalities, obesity and the like are likely to lead to inadequatesleep. Sleep disorders also occur as adverse reactions to many drugs.For example, antipyretics, antiallergenic remedies, gastrointestinaldrugs such as H2 blockers induce drowsiness. Furthermore, brain functiondisorders, e.g., schizophrenia, bipolar disorders, Alzheimer's disease,Parkinson's disease are sometimes accompanied by sleep disorders.

In general, the quality and quantity of sleep decrease with age.Experiencing difficulty in falling asleep, early wakeups, diminishedwake-sleep rhythms between day and night, decreased REM sleep, decreasedslow wave sleep and the like, many people in their senescence aresomewhat dissatisfied with their sleep. Furthermore, many prescribeddrugs (for symptoms other than sleep-related ones) disturb sleep asadverse reactions, and most elderly people are on medication with one ormore drugs prescribed; it is somewhat difficult to elucidate the causesof their complaints regarding sleep and take countermeasures. Describedbelow are some currently available therapeutic drugs for sleepdisorders.

Central Nervous Stimulants

Amphetamine or chemically synthesized stimulants with similar structurehave long been used to suppress narcolepsy and daytime drowsiness inshift works. As an indirect adrenergic agonist, amphetamine potentlystimulates the central nervous system by promoting the release ofnoradrenaline and dopamine, inhibiting their reuptake, and inhibitingmonoamine oxidase (MAO). Its use is prohibited in Japan for the reasonof adverse reactions in prolonged use or overuse. Modafinil is used inthe US since it is unlikely to produce habituation and adversereactions, although its action point remains unknown. Contained infoods, caffeine exhibits stimulatory action; it is thought to be safewhen taken in appropriate amounts, but it causes mild dependency.

Sleep-Inducing Drugs

Commonly prescribed sleep-inducing drugs include brotizolam (Lendormin),triazolam (Halcion), flunitrazepam (Rohypnol), Silece, Amoban and thelike; these act mainly on receptors of the inhibitory neurotransmitterGABA; adverse reactions such as motor disorders, memory disorders, drugdependence, and carryover effects are problematic in long-term use.

Drugs that are more effective on GABA-A receptors, e.g., zolpidem(Ambien), zaleplon (Sonata), zopiclone (Imovane), and eszopiclone(Lunesta), all decrease REM sleep to promote sleep onset, and are mostlyeffective in suppressing the transition from slow wave sleep towakefulness. These sleep-inducing drugs are also effective as sedatives,and have been reported to produce unusual behavior as adverse reactionswhile the user is in an anti-wake state.

As such, the sleep-inducing drugs and central nervous stimulants actdirectly on the neurotransmitter pathway, so that their effects usuallyoccur instantaneously; they must be taken just before expecting aneffect (within several hours). Because the targeted neurotransmitterpathway is not associated exclusively with sleep, they cause seriousdisorders when taken in large amounts. Additionally, prolonged use leadsto a reduction in the responsiveness of the neurotransmission pathway,which can cause drug dependence. Furthermore, the rebound phenomenonfollowing drug discontinuation is considerable to the extent of likelyhabituation, thus increasing the risk of drug dependence.

Although melatonin is prescribed for mild cases of sleep disorders,especially for those due to a shift of circadian rhythm, it is notpositively prescribed by specializing physicians because of a lack ofdifference in clinical efficacy compared with phototherapy.

N-acetyl-D-mannosamine, an isomer of N-acetyl-D-glucosamine, is knownas, for example, a starting material for the enzymatic synthesis ofsialic acid (N-acetyl-neuraminic acid), which serves as a medicament anda starting material for other medicaments. Also, N-acetyl-D-mannosaminepermits enzymatic synthesis of sialic acid derivatives from derivativesthereof, hence an industrially important substance. In a known method ofproducing N-acetyl-D-mannosamine, the molar conversion yield ofN-acetyl-mannosamine from N-acetyl-glucosamine in isomerizing the latterunder alkaline conditions is increased by the addition of boric acid orborate (JP-A-HEI-10-182685). Another known method is such that sialicacid, as the substrate, is reacted with N-acetyl-neuraminate lyase toproduce N-acetyl-D-mannosamine (JP-A-2001-78794). A method has beenproposed wherein the acrylated form of N-mannosamine is contacted withcells to regulate lectin binding to cell surfaces or to regulate theproliferation of nerve cells (U.S. Pat. No. 6,274,568).

N-acetyl-D-mannosamine is utilized as a starting material for thesynthesis of sialic acid or an intermediate for medicaments. As thesituation stands, however, it is not used as a final product inmedicaments or foods. Furthermore, there is no knowledge thatN-acetyl-D-mannosamine is effective in ameliorating brain hypofunctionand in ameliorating sleep disorders.

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention has been developed in view of the above-describedcircumstances, and is directed to providing an effective and highly safeagent, medicament and the like for ameliorating various disorders causedby brain hypofunction.

Means of Solving the Problems

The present inventors extensively investigated to solve theabove-described problems and, as a result, unexpectedly found thatN-acetyl-D-mannosamine improves memory, significantly extends REM sleeptime in the sleep rhythm, and normalizes the wake-sleep rhythm from itsdisturbance in animal experiments using old animals. The presentinventors conducted further investigations, and have completed thepresent invention.

Accordingly, the present invention relates to the following:

[1] An agent for preventing or ameliorating a brain hypofunctioncomprising N-acetyl-D-mannosamine.

[2] The preventing or ameliorating agent according to [1] above, whereinthe brain hypofunction is aging-related brain hypofunction.

[3] The preventing or ameliorating agent according to [1] or [2] above,wherein the agent is intended to prevent or ameliorate a disorderselected from the group consisting of sleep disorders, place memorydisorders, object memory disorders, affective disorders and decrease inmotor function.[4] An agent for preventing or ameliorating a REM sleep disorder,comprising N-acetyl-D-mannosamine.[5] The preventing or ameliorating agent according to any one of [1] to[4] above, wherein the agent is a medicament.[6] The preventing or ameliorating agent according to any one of [1] to[4] above, wherein the agent is a functional health food or a foodadditive.[7] A pharmaceutical composition for preventing, ameliorating ortreating a disorder due to a brain hypofunction, comprising an effectiveamount of N-acetyl-D-mannosamine and a pharmaceutically acceptablecarrier.[8] The pharmaceutical composition according to [7] above, wherein thedisorder is due to aging-related brain hypofunction.[9] The pharmaceutical composition according to [7] or [8] above,wherein the disorder is selected from the group consisting of sleepdisorders, place memory disorders, object memory disorders, affectivedisorders and decrease in motor function.[10] A pharmaceutical composition for preventing, ameliorating ortreating a REM sleep disorder, comprising an effective amount ofN-acetyl-D-mannosamine and a pharmaceutically acceptable carrier.[11] A food comprising N-acetyl-D-mannosamine added thereto.[12] Use of N-acetyl-D-mannosamine for producing a medicament forpreventing, ameliorating or treating a disorder due to a brainhypofunction.[13] The use according to [12] above, wherein the disorder is due toaging-related brain hypofunction.[14] The use according to [12] or [13] above, wherein the disorder isselected from the group consisting of sleep disorders, place memorydisorders, object memory disorders, affective disorders and decrease inmotor function.[15] Use of N-acetyl-D-mannosamine for producing a medicament forpreventing, ameliorating or treating a REM sleep disorder.[16] A method of preventing, ameliorating or treating a disorder due toa brain hypofunction, comprising the step of administering an effectiveamount of N-acetyl-D-mannosamine to a subject in need thereof.[17] The method according to [16] above, wherein the disorder is due toaging-related brain hypofunction.[18] The method according to [16] above, wherein the disorder isselected from the group consisting of sleep disorders, place memorydisorders, object memory disorders, affective disorders and decrease inmotor function.[19] A method of preventing, ameliorating or treating a REM sleepdisorder, comprising the step of administering an effective amount ofN-acetyl-D-mannosamine to a subject in need thereof.[20] A method of preventing or ameliorating brain hypofunction,comprising the step of allowing an effective amount ofN-acetyl-D-mannosamine to be taken by a subject in need thereof.[21] The method according to [20] above, wherein the brain hypofunctionis aging-related brain hypofunction.[22] The method according to [20] or [21] above, wherein the method isintended to prevent or ameliorate a disorder selected from the groupconsisting of sleep disorders, place memory disorders, object memorydisorders, affective disorders and decrease in motor function.[23] A method of preventing or ameliorating a REM sleep disorder,comprising the step of allowing an effective amount ofN-acetyl-D-mannosamine to be taken by a subject in need thereof.[24] A commercial package comprising the preventing or amelioratingagent according to any one of [1] to [4] and [6] above, and a printedmatter bearing an explanation concerning the preventing or amelioratingagent, stating that the preventing or ameliorating agent can be used, orshould be used, to prevent or ameliorate a brain hypofunction.[25] A commercial package comprising the pharmaceutical compositionaccording to any one of [7] to [10] above, and a printed matter bearingan explanation concerning the pharmaceutical composition, stating thatthe pharmaceutical composition can be used, or should be used, toprevent, ameliorate or treat a disorder due to a brain hypofunction.

Effect of the Invention

According to the preventing or ameliorating agent for brain hypofunctionof the present invention, it is possible to improve metabolism byactivating various cells in a living organism, to thereby delay decreasein brain function or recover from the decreased brain function. Thiseffect is believed to occur since the active ingredientN-acetyl-D-mannosamine is supplied as a promoter of sugar metabolisminto individual cells and eventually improves brain function. Therefore,the pharmaceutical composition of the present invention, which comprisesN-acetyl-D-mannosamine as an active ingredient, is capable ofpreventing, ameliorating or treating various central diseases thatdevelop with brain hypofunction (dementia, dementia of Alzheimer type,dementia with Lewy bodies, frontotemporal lobar dementia, sleepdisorders, insomnia, arousal disorders, circadian rhythm sleepdisorders, delayed sleep phase syndrome, advanced sleep phase syndrome)and the like by acting to improve the metabolism in the whole body of aliving organism. The food of the present invention is safe because it isbased on the monosaccharide N-acetyl-D-mannosamine; when takenroutinely, it is expected to prevent or ameliorate brain hypofunction.

The preventing or ameliorating agent of the present invention for sleepdisorders, particularly for REM sleep disorders, makes it possible toextend REM sleep time that has once decreased due to aging and the like,to improve the quality and quantity of sleep, and concurrently torestore the sleep wake rhythmic cycle between day and night. This effectbegins to be evident on day 2 after the start of administration of theingredient N-acetyl-D-mannosamine, but the sleep induction effect doesnot appear soon after the start of administration as with conventionalsleep-inducing drugs. Additionally, the improvements of the quality ofsleep and the like last for a given period (1 to 2 days) even aftercompletion of administration, but then they disappear. Sinceadministration with free access to water is also effective, the methodof formulation is not limited. Nor is there any limitation on the timethe formulation is taken because the sleep-wake rhythm does not shiftafter ingestion. Hence, the preventing or ameliorating agent of thepresent invention for sleep disorders, particularly for REM sleepdisorders, exhibits effects that are completely different from those ofconventional sleep-inducing drugs and central nervous stimulants;therefore, it is evident that the preventing or ameliorating agent ofthe present invention exhibits its pharmacological effect by an actionmechanism different from that for conventional drugs that target theneurotransmitter pathway. The pharmaceutical composition of the presentinvention and the food of the present invention, which compriseN-acetyl-D-mannosamine as an active ingredient, are safe because theyare based on N-acetyl-D-mannosamine, a monosaccharide occurring inliving organisms by nature, and are expected to prevent or amelioratesleep disorders when taken routinely.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the protocol for object and place recognition taskexperiments, wherein drug M indicates ManNAc.

FIG. 2 shows the items for measurement in the object and placerecognition task experiments.

FIG. 3 is a graphic representation of the results of an open field testto compare old mice and young mice in terms of distance moved and timein central area in an unfamiliar open field.

FIG. 4 is a graphic representation of the results of object and placerecognition tasks.

FIG. 5 is a graphic representation of the influences of age on sleep andwake stages using young, middle-aged and old mice. In FIG. 5A, thevertical axis indicates the ratio of wake time in a day (24 hours). InFIG. 5B, the vertical axis indicates the ratio of REM sleep time in aday. In FIG. 5C, the vertical axis indicates the ratio of slow wavesleep time in a day.

FIG. 6 shows the results of measurements of locomotor activity, bodytemperature, electroencephalograms and electromyograms in young mice andin middle-aged mice receiving N-acetyl-D-mannosamine (ManNAc), in thelight phase (12:00-20:00).

FIG. 7 shows the results of measurements of locomotor activity, bodytemperature, electroencephalograms and electromyograms in young mice andin middle-aged mice receiving N-acetyl-D-mannosamine (ManNAc), in thedark phase (0:00-8:00).

FIG. 8 is a graphic representation of the influences of administrationof N-acetyl-D-mannosamine on wake, REM sleep and slow wave sleep inyoung mice and middle-aged mice. In FIG. 8A, the vertical axis indicatesthe ratio of wake time in a day (24 hours). In FIG. 8B, the verticalaxis indicates the ratio of REM sleep time in a day. In FIG. 8C, thevertical axis indicates the ratio of slow wave sleep time in a day.

FIG. 9 shows the results of measurements of heart rate, body temperatureand locomotor activity in an experiment of recovery from aging-relatedsleep disorders, wherein M administration indicates duration ofadministration of N-acetyl-D-mannosamine.

MODES FOR EMBODYING THE INVENTION

The preventing or ameliorating agent for brain hypofunction of thepresent invention (hereinafter sometimes simply referred to as “agent”)comprises N-acetyl-D-mannosamine.

In the present invention, N-acetyl-D-mannosamine (hereinafter sometimesabbreviated ManNAc) is the N-acetyl-form of D-mannosamine represented bythe formula (I):

In the present invention, the term N-acetyl-D-mannosamine is not limitedto the simple substance represented by the formula (I) above, butencompasses the salts thereof, solvates thereof, and derivativesthereof.

Salts of N-acetyl-D-mannosamine include pharmacologically acceptablesalts, e.g., salts with inorganic acids, salts with organic acids, saltswith basic or acidic amino acids and the like.

Examples of salts with inorganic acids include salts with hydrochloricacid, hydrobromic acid, nitric acid, sulfuric acid, phosphoric acid andthe like.

Examples of salts with organic acids include salts with benzoic acid,formic acid, acetic acid, trifluoroacetic acid, fumaric acid, oxalicacid, tartaric acid, maleic acid, citric acid, succinic acid, malicacid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acidand the like.

Examples of salts with basic amino acids include salts with arginine,lysine, ornithine and the like; examples of suitable salts with acidicamino acids include salts with aspartic acid, glutamic acid and thelike.

Solvates of N-acetyl-D-mannosamine preferably include hydrates (e.g.,monohydrate, dihydrate and the like), ethanolates and the like.

Derivatives of N-acetyl-D-mannosamine include those represented by theformula (II) below.

[wherein each of R¹, R², R³, R⁴ and R⁵ independently represents hydrogen(H), R⁶, —C(═O)R⁶, —C(═O) OR⁶, or —C(═O)NR⁶R⁷; R⁶ represents anoptionally substituted C₁-C₇ linear or cyclic hydrocarbon; R⁷ representshydrogen (H), an optionally substituted C₁-C₇ linear or cyclichydrocarbon.]Useful substituents are F, Cl, and Br.

The N-acetyl-D-mannosamine used may be a commercial product, or may beprepared by a method known per se. Useful methods of producingN-acetyl-D-mannosamine include, but are not limited to, a methodinvolving isomerizing N-acetyl-glucosamine under alkaline conditions(JP-A-HEI-10-182685) and a method involving a reaction of sialic acid asthe substrate with N-acetyl-neuraminate lyase (JP-A-2001-78794).

In the present invention, “brain hypofunction” refers to a state wherethe function of the brain is subnormal due to various factors in theprocesses from animal genesis to death, compared with the brain functionof the same animal in the mature stage. A representative cause of brainhypofunction is senescence; other causal factors include, but, becauseof the involvement of a variety of factors in individual animals, arenot limited to, stress, the environment, hereditary diseases, organicdisorders and the like. Although the brain maturity stage variesdepending on the species of animal, and cannot be generalized, adulthoodmay usually serve as an indicator. The stage occurs at 15 to 30 years ofage for humans and 7 to 20 weeks of age for mice.

The brain hypofunction to which the present invention is applied ispreferably aging-related brain hypofunction; brain hypofunctionmanifests itself in the form of sleep disorders, place memory disorders,object memory disorders, affective disorders, decrease in motor functionand the like.

Sleep disorders include sleep volume reductions and sleep qualityreductions, the former manifesting themselves as increased sleep onsettime, inadequate sleep time due to premature arousal and the like, andthe latter developing as symptoms such as bedtime shifts, decreased deepsleep (non-REM sleep), sleep interruptions due to premature arousal, andnaps in active time zones. Sleep disorders occur irrespective of thepatient's age; especially the quality of sleep decreases with aging. Adiagnosis is made by a test consisting of a plurality of inquiries, andis established by electroencephalography or by polysomnography, whichmeasures multiple parameters, including electroencephalograms. Diagnosescan be classified according to internationally recognized criteria (TheInternational Classification of Sleep Disorder, ICSD).

In the present invention, “REM sleep” refers to a state of sleepcharacterized by active brain function and relaxed skeletal muscles.Whether a living organism is in the REM sleep stage can be determined byanalyzing electromyograms (EMG) or electroencephalograms (EEG). The REMsleep stage can also be identified by observing the rapid movement ofeyeballs and increased heart rates. Meanwhile, “non-REM sleep” refers toa state of sleep characterized by suppressed brain function. Non-REMsleep can also be classified into four categories, from stage 1 (lightsleep) to stage 4 (deep sleep); it is said that the transition to REMsleep occurs in stage 2.

In the present invention, “a REM sleep disorder” refers to a poor or badcondition in a living organism due to a REM sleep time reductionassociated with aging or another reason. REM sleep disorders can becomedirect or indirect causal factors for, for example, insomnia, arousaldisorders, circadian rhythm aberrations, metabolic or gastrointestinaldisorders such as anorexia and weight loss, sensations of fatigue suchas generalized lassitude and fatigability, cardiovascular disorders suchas hypertension and heart failure, and central functional disorders suchas of cognitive function and learning ability. In the present invention,these symptoms or conditions can be the subjects of prevention,amelioration or treatment.

A disorder of place memory refers to a disturbance of the recognition ofthe spacial position of self at a given time point, a disturbance ofrecognition memory for a place to which the subject has ever been andthe like. A disorder of object memory refers to a disturbance of therecognition of an object perceived by contact and the like, a disorderof memorizing the experience and the like. These memory disorders can bemeasured by, for example, the place recognition task and objectrecognition task shown in Example 1 and FIG. 2.

Specifically, the agent of the present invention can be administered ortaken for the purpose of preventing or ameliorating a disorder selectedfrom the group consisting of the aforementioned sleep disorders(particularly REM sleep disorders), insomnia, arousal disorders,circadian rhythm sleep disorders, delayed sleep phase syndrome, advancedsleep phase syndrome, place memory disorders, object memory disorders,dementia, dementia of Alzheimer type, dementia with Lewy bodies andfrontotemporal lobar dementia.

For these purposes, the agent of the present invention can be used as amedicament or functional health food or food additive in the form ofN-acetyl-D-mannosamine, alone or after being blended with excipients(e.g., lactose, sucrose, starch, cyclodextrin and the like), sometimesfurther blended with flavors, dyes, seasoning agents, stabilizers,preservatives and the like, into tablets, pills, granules, finegranules, powders, pellets, capsules, solutions, emulsions, suspension,syrups, troches and the like. The agent of the present invention canalso be used as a research reagent.

The amount of N-acetyl-D-mannosamine contained in the agent of thepresent invention is not particularly limited, as far as the effect ofthe present invention is obtained; the amount is normally 0.0001% to100% by weight, preferably 0.001% to 99.9% by weight.

The present invention also provides a pharmaceutical composition forpreventing, ameliorating or treating a disorder due to brainhypofunction, comprising an effective amount of N-acetyl-D-mannosamineand a pharmaceutically acceptable carrier.

Examples of pharmaceutically acceptable carriers include, but are notlimited to, excipients (e.g., lactose, sucrose, dextrin,hydroxypropylcellulose, polyvinylpyrrolidone and the like),disintegrants (e.g., starch, carboxymethylcellulose and the like),lubricants (e.g., magnesium stearate and the like), surfactants (e.g.,sodium lauryl sulfate and the like), solvents (e.g., water, saline,soybean oil and the like), preservatives (e.g., p-hydroxybenzoate andthe like) and the like.

The effective amount of N-acetyl-D-mannosamine is not particularlylimited, as far as an effect as a medicament is exhibited, and theamount is normally 0.0001% to 99.5% by weight, preferably 0.001% to99.0% by weight.

The disorder to be prevented, ameliorated or treated with thepharmaceutical composition of the present invention is due to a brainhypofunction, preferably aging-related brain hypofunction. Disorders dueto brain hypofunction include sleep disorders, especially thoseaccompanied by REM sleep attenuation (herein, simply referred to as “REMsleep disorders”), place memory disorders, object memory disorders,dementia, dementia of Alzheimer type, dementia with Lewy bodies,frontotemporal lobar dementia and the like. The REM sleep disorders arepreferably spontaneously developing sleep disorders that accompanysenile aging and the like, including Alzheimer's disease, REM sleepbehavioral disorders, narcolepsy, sleep-wake transition disorders andthe like.

From another viewpoint, animals have individual differences; disordersdue to brain hypofunction develop as a broad range of symptoms, and cansometimes be classified or diagnosed as particular diseases. Therefore,the pharmaceutical composition of the present invention can also be usedto prevent, ameliorate or treat, for example, schizophrenia (preferablylate-onset schizophrenia), Alzheimer's disease (preferably senileAlzheimer's disease), depression, dementia, dementia of Alzheimer type,dementia with Lewy bodies, frontotemporal lobar dementia, sleepdisorders, insomnia, arousal disorders, circadian rhythm sleepdisorders, delayed sleep phase syndrome, advanced sleep phase syndromeand the like.

The agent or pharmaceutical composition of the present invention can besafely administered to mammals (e.g., mice, rats, rabbits, cats, dogs,bovines, horses, monkeys, humans) orally or non-orally.

The present invention provides a food comprising N-acetyl-D-mannosamineadded thereto.

The “food” of the present invention means any food in the general sense,and includes general foods, including what are called health foods, aswell as functional health foods such as foods for specified health usesand foods with nutrient function claims, specified in the functionalhealth food system by Japan's Ministry of Health, Labor and Welfare;nutritional supplements, animal feeds and the like are also encompassedin the scope of the food of the present invention.

In food use applications, N-acetyl-D-mannosamine can be used ascontained in, for example, general foods (including what are calledhealth foods) such as bread and confectionery. It is also possible toprepare N-acetyl-D-mannosamine, along with excipients (e.g., lactose,sucrose, starch and the like), sometimes further with flavors, dyes andthe like, into preparations such as tablets, pills, granules, finegranules, powders, pellets, capsules, solutions, emulsions, suspensions,syrups and troches, and used as functional health foods such as foodsfor specified health uses and foods with nutrient function claims, ornutritional supplements. The food of the present invention is alsoapplicable for feed applications, and can be taken or administered asadded to ordinary feeds in poultry, farm animals and the like.

When taken as a food or feed, approximate figures of the number of timesthe food or feed is taken per day and the amount taken per time arecalculated to define the daily intake amount, and the amount ofN-acetyl-D-mannosamine contained in the daily intake amount of the foodor feed is determined. The amount of N-acetyl-D-mannosamine containedcan be determined on the basis of the doses described below.

The agent of the present invention can also be provided as a commercialpackage also comprising a printed matter bearing an explanationconcerning the preventing or ameliorating agent, stating that the agentcan be used, or should be used, to prevent or ameliorate brainhypofunction.

The pharmaceutical composition of the present invention can also beprovided as a commercial package further comprising a printed matterbearing an explanation concerning the pharmaceutical composition,stating that the pharmaceutical composition can be used, or should beused, to prevent, ameliorate or treat disorders due to brainhypofunction.

To allow the N-acetyl-D-mannosamine contained to exhibit its biologicalaction effectively, the food of the present invention is preferably usedas a food for specified health uses or a food with nutrient functionclaims. In that situation, it is recommended that the product be labeledwith the statement “to be used to prevent or ameliorate brainhypofunction”, “improve the quality of sleep and wake-up”, and“well-organize daily activities”.

The amount of the agent, food or pharmaceutical composition of thepresent invention taken or administered varies depending on therecipient's age, body weight and health status, and cannot begeneralized. For example, it is preferable that 0.1 to 10 g, preferably0.2 g to 7 g, calculated as N-acetyl-D-mannosamine, be taken or eatenper day for an adult in one to several divided doses, usually in thefour of a food for the purpose of maintaining and enhancing health orpreventing or ameliorating brain hypofunction, and usually in the formof a medicament or food for the purpose of treating a disorder due tobrain hypofunction or restoring health.

The dosage and administration of the medicament (agent or pharmaceuticalcomposition) of the present invention is not particularly limited, asfar as the route of administration ensures a preventive and therapeuticeffect on the above-described disorders or diseases. For example, thesame can be administered by parenteral administration (intravenousadministration, intramuscular administration, direct administration intotissue, intranasal administration, intradermal administration,intramedullary administration and the like) or oral administration. Forhuman application, in particular, the medicament of the presentinvention can be administered by intravenous, intramuscular or oraladministration. There is no limitation on the dosage form; themedicament of the present invention can be administered as variousdosage forms, e.g., oral formulations (granules, powders, tablets,capsules, syrups, emulsions, suspensions and the like), injections, dripinfusions, external formulations (nasal preparations, transdermalpreparations, ointments and the like).

The present invention also provides a use of N-acetyl-D-mannosamine forproducing a medicament for preventing, ameliorating or treating brainhypofunction. Specifically, the present invention provides a method ofproducing a medicament for preventing, ameliorating or treating brainhypofunction using N-acetyl-D-mannosamine.

For producing the medicament of the present invention, methods known perse in the field of drug formulation can be used without limitations.

Contained at very low abundance in human cells as an intermediate,N-acetyl-D-mannosamine has no toxicities (e.g., acute toxicity, chronictoxicity, genotoxicity, reproductive toxicity, cardiac toxicity, druginteractions, carcinogenicity), and is believed to be highly safe inhumans.

The agent, pharmaceutical composition or food of the present inventionexhibits the following effects as shown in Examples.

(1) Improve aging-related place memory and object memory to ameliorateaging-related brain hypofunction.

(2) Prolongs REM sleep and wake times significantly and inverselyshortens non-REM sleep (slow wave sleep) time to maintain the sleep-wakerhythm at young ages.

(3) Suppress aging-related reductions of the quality of sleep,potentiates wakeful activities, and improves the quality of sleep.

EXAMPLES

The present invention is hereinafter described more specifically bymeans of the following Examples. However, the Examples only representtypical cases, and are variously modifiable, as far as the technicalconcept of the invention is not deviated from.

Example 1 Recovery from Brain Functional Disorders Such as Aging-RelatedDeteriorations of Object Memory and Place Memory Using ManNAc

1) Object and place recognition task experiments were performed on maleC57BL6/Njcl mice in three groups. Outline of the experiments is shown inFIG. 1.

Old control group: Old mice (reared from 47 to 66 weeks of age, n=10)were allowed to drink tap water ad libitum.

Old ManNAc recipient group: Old mice (reared from 47 to 66 weeks of age,n=10) were allowed to drink tap water with ManNAc (5 mg/ml) dissolvedtherein ad libitum.

Young control group: Young mice (reared from 8 to 18 weeks of age, n=10)were allowed to drink tap water ad libitum.

2) Experimental procedures: An open field test was performed to examinethe tendency toward anxiety and locomotor activity, and this wasfollowed by place recognition task and object recognition task inaccordance with conventional methods (see FIG. 2).

3) Experimental results (FIGS. 3 and 4)

Open field test (FIG. 3): Moving distance in an unfamiliar planar spacewas compared between the old mice and the young mice. Although the oldmice tended to exhibit lower locomotor activity, the difference wasstatistically insignificant (One Way ANOVA, p=0.32). An indicator of thetendency toward anxiety, i.e., time of stay in the central portion,decreased significantly in the old mice compared with the young mice(One way ANOVA with Tukey's post hoc test, p<0.001), demonstrating anincreased tendency toward anxiety. When ManNAc was administered to theold mice, this rise in the tendency toward anxiety tended to decreaseslightly, but the difference was statistically insignificant.

Place task and object task (FIG. 4): In the young mice (FIG. 4B), in theplace recognition task (“Place” in FIG. 4B), exploration time for anobject placed at a new place extended significantly (paired t-test,p<0.05), demonstrating that the mice were able to recognize and memorizethe change of the place. In the object recognition task (“object” inFIG. 4B), exploration time for a new object (“New” in FIG. 4B) extended(paired t-test, p<0.001), demonstrating that the mice were able torecognize and memorize the change of the object. In the old mice (FIG.4A), in both tests, exploration times for a new place (paired t-test,p=0.72) and a new object (paired t-test, p=0.94) did not extend;disturbances of these recognition tasks were detected. When ManNAc wasadministered to the old mice (FIG. 4C), the exploratory behavior timesfor the new place (paired t-test, p<0.05) and the new object (pairedt-test, p<0.001) normalized in all tasks; a capability of recognitionmemory equivalent to that of the young mice was shown.

Comprehensively judging from these results of the open field test, placetask and object task, it is evident that ManNAc improves place memoryand object memory without influencing total motor activity.

Example 2 Recovery from Aging-Related Sleep Disorders Using ManNAc

Mice are awake during active time in the dark phase and conversely ceasetheir activities and have a sleep in the light phase. It is known thatin aged mice, the wake-sleep rhythm is deranged to the extent of lightersleep in the light phase and decreased activities during wake time inthe dark phase. It is also known that the aging-related derangement ofwake and sleep is related to hypothalamic activity and accompanied byelevated body temperatures and increased heart rates. Because thesesymptoms are similar to those in human patients in their middle age tosenescence who complain of dissatisfaction with sleep, they serve as anappropriate model for examining the influences on sleep.

Middle-aged mice [three reared from 43 to 66 weeks of age underlight-dark cycle conditions (12-hour light phase-12-hour dark phase)]were allowed to drink ManNAc solution (5 mg/ml tap water) ad libitum.During 1 week before and after the free access to the solution,respiratory rate, body temperature, and locomotor activity weremonitored over time using a telemeter. Also analyzed wereelectroencephalograms recorded during wake and sleep times in both theManNAc non-ingestion period and the free-access period. To measureelectroencephalograms and electromyograms, a mouse electroencephalogramtransmitter (F20EET, Data Sciences) was implanted in each animal underanesthesia (pentobarbital, 30 mg/kg, i.v.), and electroencephalograms,electromyograms, body temperature, and locomotor activity werecontinuously recorded using ART (Data Sciences Company). Theelectroencephalograms thus obtained were analyzed using NeuroScore (DataSciences Company), and the sleep events were classified into REM sleepand slow wave sleep. The lengths of each sleep stage were totaled andcompared among the mice before and after administration and young mice.

Analysis of pre-administration period confirmed decreased wake time,decreased REM sleep, and increased slow wave sleep in the old mice (43to 55 weeks of age) compared with the young mice (17 to 21 weeks of age)(FIG. 5).

The electroencephalograms, electromyograms, body temperature, andlocomotor activity during the light phase (non-active phase: mice arenocturnal) and the dark phase (active phase) in the middle-aged miceobtained on day 4 after administration are shown graphically. Forcontrol, electroencephalograms, electromyograms, body temperature, andlocomotor activity in the young mice are likewise shown graphically(FIGS. 6 and 7). In the middle-aged mice receiving ManNAc, remarkablyincreased wake time, increased REM sleep, and decreased slow wave sleepbegan to be observed on day 2 to 3 after administration (FIG. 8, Table1).

TABLE 1 Sleep analysis results (daily percentage) Before administration4 days after Type (%) administration (%) Wake 1.8 2.2 Wake (major) 12.715.3 REM sleep 5.4 10.0 Slow wave sleep 80.0 72.5

Furthermore, administration of ManNAc increased the difference inlocomotor activity between the light and dark phases (FIG. 9). Withadministration of ManNAc, the change in heart rate due to behavioralchange, i.e., the difference between the light and dark phases, becameevident, whereas body temperature declined during the non-active period.These results show that ManNAc improves both the quality and quantity ofsleep, and is hence remarkably effective in inducing wake-sleep rhythmiccycle between day and night, demonstrating that ManNAc serves as aneffective ingredient for a sleep improver.

INDUSTRIAL APPLICABILITY

By taking or eating a medicament or food provided by the presentinvention, which contains ManNAc as an active ingredient, aging-relatedbrain hypofunction can be prevented, ameliorated or treated. Taking oreating a medicament or food of the present invention also makes itpossible to prevent, ameliorate or treat REM sleep disorders, whereby animprovement of the quality of sleep is expected.

The invention claimed is:
 1. A method of ameliorating or treating asleep interruption due to premature arousal in a subject in needthereof, comprising administering an effective amount ofN-acetyl-D-mannosamine to the subject.
 2. A method of ameliorating asleep interruption due to premature arousal in a subject in needthereof, comprising allowing an effective amount ofN-acetyl-D-mannosamine to be taken by the subject.
 3. The method ofclaim 2, wherein the subject is a human.
 4. The method of claim 1,wherein the subject is a human.